Olefin type thermoplastic elastomer

Abstract

An olefin type thermoplastic elastomer which satisfies the following formulae (I) to (III):where X, Y and Z are as follows: X: JIS A hardness of a molded product as measured in accordance with JIS K6253 (no unit); Y: rate of change in the weight of a molded product measured based on JIS K6258 using IRM903 oil at 120° C. (unit: %); and Z: number of granular structures on an extruded sheet surface (250 mmx1,500 mm) (unit: granular structures).

What is claimed is:  
     
       1. An olefin thermoplastic elastomer which satisfies the following formulae (I) to (III): 
       
         
             Y≦ 2 X +350  (I)  
         
       
       
         
           X≦95  (II)  
         
       
       
         
           Z≦150  (III)  
         
       
       wherein:  
       X is the JIS A hardness of a molded product measured in accordance with JIS K6253;  
       Y is the change in the weight in % of a molded product measured based on JIS K6258 using IRM903 oil at 120° C.; and  
       Z is the number of granular structures on an 250 mm×1,500 mm extruded sheet surface wherein the thermoplastic elastomer is obtained by mixing an olefin copolymer rubber having a weight average molecular weight of at least 500,000, component (A1), with a mineral oil softening agent, component (B), in an amount of from 12 to 200 parts by weight per 100 parts by weight of component (A1), to prepare an oil-extended olefin copolymer rubber component (A1B), and then mixing from 30 to 95 wt % of component (A1B) with from 5 to 70 wt % of an olefin resin component (C), wherein the total amount of components (A1B) and (C) is 100 wt %, followed by dynamic heat treatment in the presence of an organic peroxide, component (D), at a temperature lower than the one minute half life decomposition temperature of the organic peroxide.  
     
     
       2. The olefin thermoplastic elastomer according to  claim 1 , comprising domains of a crosslinked olefin copolymer rubber dispersed in an olefin resin, said domains having an average particle size of from 0.1 to 5 μm, 
       further wherein the olefin resin is dispersed an average particle size of from 0.01 to 0.5 μm in at least a part of the domains.  
     
     
       3. The olefin thermoplastic elastomer according to  claim 2 , wherein the proportion of the domains containing the dispersed olefin resin is at least 10% by area. 
     
     
       4. The olefin thermoplastic elastomer according to  claim 1 , wherein an olefin copolymer rubber having a weight average molecular weight of less than 500,000, component (A2), is mixed with component (A1) in a proportion of at most double the total weight of components (A1B) and (C). 
     
     
       5. The olefin thermoplastic elastomer according to  claim 1 , wherein after the dynamic heat treatment, component (B) is further mixed in a proportion of at most 1.5 times the total weight of the components (A1B) and (C). 
     
     
       6. The olefin thermoplastic elastomer according to  claim 4 , wherein at least one of components (A1) and (A2) is an ethylene-propylene-unconjugated diene rubber. 
     
     
       7. The olefin thermoplastic elastomer according to  claim 6 , wherein the ethylene-propylene unconjugated diene rubber has an ethylene content of from 50 to 90 wt %, a propylene content of from 5 to 50 wt % and a unconjugated diene content of from 1 to 30 wt %. 
     
     
       8. The olefin thermoplastic elastomer according to  claim 1 , wherein component (C) is a polypropylene, a propylene-α-olefin copolymer or both a polypropylene and a propylene-α-olefin copolymer. 
     
     
       9. A sheet-form molded product comprising as a substrate a composition containing the olefin thermoplastic elastomer of  claim 1 . 
     
     
       10. A laminate having a surface layer comprising as a substrate a composition containing the olefin thermoplastic elastomer of  claim 1 . 
     
     
       11. The olefin thermoplastic elastomer of  claim 1 , wherein Y+2X is at most 330. 
     
     
       12. The olefin thermoplastic elastomer of  claim 1 , wherein Y+2X is at least 60. 
     
     
       13. The olefin thermoplastic elastomer of  claim 1 , wherein X is at least 10. 
     
     
       14. The olefin thermoplastic elastomer of  claim 1 , wherein Z is at most 100. 
     
     
       15. The olefin thermoplastic elastomer of  claim 1 , wherein Z is at most 50. 
     
     
       16. The olefin thermoplastic elastomer according to  claim 1 , wherein component (A1) is selected from the group consisting of an ethylene-propylene copolymer rubber, an ethylene-propylene-unconjugated diene copolymer rubber, an ethylene-butene-unconjugated diene copolymer rubber, and a propylene-butadiene copolymer rubber. 
     
     
       17. The olefin thermoplastic elastomer of  claim 1 , wherein component (B) is a paraffin oil. 
     
     
       18. The olefin thermoplastic elastomer of  claim 1 , wherein component (C) is selected from the group consisting of a propylene resin, an ethylene resin, and a crystalline polybutene-1 resin. 
     
     
       19. The olefin thermoplastic elastomer of  claim 1 , wherein component (C) is a propylene resin. 
     
     
       20. The olefin thermoplastic elastomer of  claim 1 , wherein 
       X is 53 to 94  
       Y is from 87 to 182, and  
       Z is from 7 to 42.  
     
     
       21. An olefin thermoplastic elastomer composition comprising, a mixture of a crosslinked olefin copolymer rubber and an olefin resin dynamically heat treated with an organic peroxide at a temperature lower than the one minute half life decomposition temperature of the organic peroxide, wherein the mixture comprises from 30 to 95 wt % of an oil-extended olefin copolymer rubber (A1B), wherein (A1B) comprises an olefin copolymer rubber having a weight average molecular weight of at least 500,000 (A1) and a mineral oil softening agent (B) present in an amount of from 12 to 200 parts by weight per 100 parts by weight of component (A1); and from 5 to 70 wt % of an olefin resin (C), wherein the total amount of (A1B) and (C) is 100 wt % 
       wherein the composition satisfies the following formulae (I) to (III):  
       
         
             Y≦− 2 X+ 350  (I)  
         
       
       
         
           X<95  (II)  
         
       
       
         
           Z≦150  (III)  
         
       
       wherein:  
       X is the JIS A hardness of a molded product measured in accordance with JIS K6253;  
       Y is the change in the weight in % of a molded product measured based on JIS K6258 using IRM903 oil at 120° C.; and  
       Z is the number of granular structures on an 250 mm×1,500 mm extruded sheet surface.  
     
     
       22. The olefin thermoplastic elastomer composition according to  claim 21 , wherein the proportion of the domains containing the dispersed olefin resin is at least 10% by area. 
     
     
       23. The olefin thermoplastic elastomer composition according to  claim 21 , further comprising an olefin copolymer rubber having a weight average molecular weight of less than 500,000 (A2) present in a proportion of at most double the total weight of (A1B) and (C). 
     
     
       24. The olefin thermoplastic elastomer composition according to  claim 23 , wherein at least one of (A1) and (A2) is an ethylene-propylene-unconjugated diene rubber. 
     
     
       25. The olefin thermoplastic elastomer composition according to  claim 24 , wherein the ethylene-propylene unconjugated diene rubber has an ethylene content of from 50 to 90 wt %, a propylene content of from 5 to 50 wt % and a unconjugated diene content of from 1 to 30 wt %. 
     
     
       26. The olefin thermoplastic elastomer composition according to  claim 21 , wherein (C) is a polypropylene, a propylene-α-olefin copolymer or both polypropylene and propylene-α-olefin. 
     
     
       27. A sheet-form molded product comprising as a substrate a composition containing the olefin thermoplastic elastomer of  claim 21 . 
     
     
       28. A laminate having a surface layer comprising as a substrate a composition containing the olefin thermoplastic elastomer of  claim 21 . 
     
     
       29. The olefin thermoplastic elastomer composition of  claim 21 , wherein Y+2X is at most 330. 
     
     
       30. The olefin thermoplastic elastomer composition of  claim 21 , wherein Y+2X is at least 60. 
     
     
       31. The olefin thermoplastic elastomer composition according to  claim 21 , wherein (A1) is selected from the group consisting of an ethylene-propylene copolymer rubber, an ethylene-propylene-unconjugated diene copolymer rubber, an ethylene-butene-unconjugated diene copolymer rubber, and a propylene-butadiene copolymer rubber. 
     
     
       32. The olefin thermoplastic elastomer composition according to  claim 21 , wherein domains of the crosslinked olefin copolymer rubber are dispersed in the olefin resin, said domains having an average particle size of from 0.1 to 5 μm, further wherein the olefin resin is dispersed an average particle size of from 0.01 to 0.5 μm in at least a part of the domains.